use of EXTRA_NAMESPACE with qt6_add_protobuf ends up in front of Timestamp

I build several libraries of qtprotobuf-generated classes.

I see that google/protobuf/timestamp.proto is now included in QtProtobufWellKnownTypes, that's great! (is descriptor.proto going to make it in anytime soon?)

I used to include timestamp.proto in one of my libraries (because QtProtobufWellKnownTypes didn't) and so my EXTRA_NAMESPACE (=SSProto) would end up in front of that generated class, like this: SSProto::google::Protobuf:Timestamp.

However, in spite of the fact that I have removed timestamp.proto from the library I create, the generated code for my other .proto files (that `import "google/protobuf/timestamp.proto"`) still prepend that class name with my EXTRA_NAMESPACE. This is curious because I have never had that issue with any.proto, but that's wrapped enough that maybe it's a totally different issue.

Complication: I'm using EXTRA_NAMESPACE in order to avoid a symbol conflict when loading a plugin that links to the standard protobuf library. I'm afraid (haven't tried it, since I can't get my app to compile yet) that the google::Protobuf::Timestamp class in QtProtobufWellKnownTypes will clash with something generated using the standard protobuf generator. Is that an unfounded fear?